Pneumatic tool



Oct 24, 1939.

w. A. SMITH, .1R

PNEUMATIC TOOL Filed May 23' 1938 /1/5 Arm/win Patented Oct. 24, 1939PATENT oFFicE PNEUMATIC TOOL William A. Smith, Jr., Dayton, Ohio,assigner to The Buckeye Portable Tool Company, Dayton, Ohio, acorporation of Ohio Application May 23, 193s, serial No. 209,478

4 Claims.

This invention relates to pneumatic tools and more particularly toautomatic valve mechanism for controlling the admission of air to the ycylinder to a piston type tool.

One object of the invention is to provide a pneumatic tool with anautomatic valve which will be simple in construction and e'icient inoperation.

A further object of the invention is to provide a valve of such acharacter that the action of the air on the movable valve member willmove the same positively to the limit of its movement in eitherdirection and will prevent the uttering of the valve member.

A further object of the invention is to provide a valve which may beeasily manufactured and assembled and which will be compact in form.

Other objects of the invention may appear as the mechanism is described.

In the accompanying drawing Fig. l. is a longitudinal section takenthrough a pneumatic tool embodying the invention, on the lines I-I ofFigs. 3 and 4; Fig. 2 is a transverse section taken on the line 2-2 ofFig. l; Fig. 3 is a transverse section taken on the line 3 3 of Fig. l;and Fig. 4 is a transverse section taken on the line 4 4 of Fig. l.

In the drawing I have illustrated one embodiment of my invention andhave shown the same as embodied in a pneumatic hammer of a well knowntype. It will be understood, however, that the valve mechanism may takevarious forms and may be embodied in pneumatic tools of various kinds.

In the particular embodiment here illustrated the pneumatic hammercomprises a body the forward portion 5 of which constitutes a cylinderin which is mounted a piston or hammer 6, this hammer being arranged tostrike the shank 'I of the tool mounted in the forward end of thecylinder. The rear portion of the body is here shown in the form ofr arhousing or cap 8 which is screw threaded onto the rear portion of acylinder. Rigidly secured to this rear portion or cap is a handle 9 bywhich the tool may be supported and manipulated, and this handle isprovided with an air conduit II] leading to the Valve mechanism, as willbe hereinafter described. At one end the air conduit is provided with ameans, such as a fitting I I, for connecting the same with a source ofsupply for air under pressure, in a well known manner. The handle isalso provided with a manually operable master valve I2 for controllingthe passage of air through the conduit IB, this valve being of a wellknown type.

'Ihe cylinder 5 is provided with longitudinal inlet conduits I3 whichare connected at their forward ends by ports I4 with the forward end ofthe cylinder, in advance of the piston. These conduits extend throughthe rear end of the cylinder and are connected with the valve mechanism,as will be presently described. The cylinder is also provided with aseries of exhaust conduits I5, there being in the present instance sixof these conduits. The forward portion of each exhaust conduit isconnected with the interior of the cylinder by ports I6 and I 'l spacedone from the other. The rear end of each exhaust conduit is connected byone or more ports I8 with a circumferential exhaust channel i8 having aseries of openings 20 in the outer wall thereof.

The rear or cap portion of the body has that part thereof in the rear ofthe cylinder enlarged to form a cavity and in this cavity is mounted avalve unit ZI which is preferably circular in form and is of a diametersomewhat less than the diameter of the cavity in the cap so as to formbetween the valve unit and the circumferential wall of the cavity acircumferential passageway 22 which is in open communication with theair conduit Iii in thehandle 9. Preferably the conduitl Ii) is enlargedat its point of connection with the passageway, as shown at 23, toprovide a better. distribution of the air in the passageway.

The valve unit comprises a front member or plate 2t, here shown ascircular in form and as having. a central opening 25 in opencommunication with the rear end of the cylinder, and a rearwardly facingannular channel 26 surrounding the opening. A rear member or plate 21 isspaced a short distance to the rear of the front member 2li and isprovided with a central opening 28 which communicates with the inletconduits i3 of the cylinder, as will be presently described, and is alsoprovided with a forwardly facing annular channel 29 which is arranged inopposed relation to the rearwardly facing channel 26 in the front member24. Interposed between the outer portions of the front and rear members24 and 2'! is an intermediate member 3U which is annular in form andwhich preferably has its inner edge projecting slightly into the spacebetween the opposed annular channels of the front and rear members. Thisintermediate member isprovided with a series of substantially radialports 3i which connect the circumferential passageway 22 with theannular channels 26V and 29. These three parts of the valve mechanismare rigidly connected one to the other tez and to the cylinder, as bymeans of dowel pins, 32, the pins being so arranged that the severalparts can be assembled only in their proper relation one to the otherand to the cylinder. Each stationary member is provided near the edgethereof with two openings, the corresponding openings in the threemembers being arranged in alinement one with the other and with' therespective inlet conduits I3, and thus provide extensions 33 of theinlet conduits. These extensions 33 are in open communication with thecentral opening 28 of the rear stationary member 21, this member beingprovided in the present instance with a transverse bore 34 which is inopen communication with the opening 28 and with the extensions 33 of therespective inlet conduits.

A movable valve member 35 is mounted between the inner portions of thefront and rear stationary members 24 and 27, so as to separate theopenings 25 and 28 in said members, and the peripheral portion of thismovable valve member projects into the space between the opposed annularchannels 2E and 29 and has a snug sliding fit within the annularintermediate member 39. Preferably this annular intermediate member isprovided with a circumferential peripheral groove 36, with which theports 3l communicate, the front and rear walls of the groove having aseries of notches 3'! to connect the same with the respective annularchannels 26 and 29.. The peripheral edge of the movable valve member 35is also preferably provided with one or more circumferential peripheralgrooves 38 arranged in line with the groove 3l and the ports 3l. Thusthe air entering the grooves 31 and 38 from the ports 3l will be sodistributed as to materially reduce its turbulence as it passes throughthe notches 31 to the annular channels 26 and 29. The movable valvemember 35 is of a thickness slightly less than the distance betweenthose portions of the front and rear stationary members 24 and 21adjacent the openings therein, so that it is capable of a slight foreand aft movement and when in engagement with one stationary member itwill be spaced from the other Stationary member a distance suflicient toconnect rthe annular passageway and opening of saidrother member. Thecontacting surfaces of the movable valve member and of the'stationary.`members are iinished to provide a close contact between the same whichwill prevent any appreciable passage of air between the movable member`and the stationary member with which it is in contact.

When the piston is in its foremost position, as shown in Fig. l, thevalve member will ordinarily be in its forward position, that is, incontact with the stationary member 24, and the channel 29 of the rearmember will be in open communication with the opening 28 in that member,which opening is in open communication with the forward end of thecylinder. Therefore, when the master valve is opened, the air will passthrough the circumferential passageway 22 and ports 3l to the annularchannel 29, thence to the opening 29 and to the forward end ofthecylinder, thereby moving the piston rearwardly. When the forward endof the piston passes the foremost exhaust port I6 the air pressurethereon will be relieved and the piston will complete its rearwardmovement b-y momentum. The air which is compressed back of the pistonwill move the movable` valve member to its rearmost position so as tointerrupt the communication between the annular channel 29 and opening28 of the rear stationary member and to establish communication betweenthe annular channel 26 and opening 25 of the front stationary member,thus admitting air to the rear end of the cylinder and imparting aforward movement to the piston. The rear end of the piston will pass therear exhaust port I1 before the Vpiston has completed tis movement andthis forward movement will be completed by momentum, thus causing thatpiston to strike the shank of the tool. When the forward end of thepiston closes the exhaust port l5 the air in front of the piston will beforced rearwardly through the inlet conduits I3 and will act on the rearface ofthe movable valve member to move the samey forwardly, as soon asthe exhaust port l 'l has been opened to relieve the pressure within therear portion of the cylinder, thus again admitting air to the front endof the cylinder and causing the piston to be retracted. This cycle ofoperations is repeated with great rapidity so long as the master valveis open.

While I have shown and described one embodiment of my invention I wishit to be understood that I do Vnot desire to be limited to the detailsthereof as various modications may appear to a person skilled in theart. y

Having now fully described my invention, what I claim as new and desireto secure by Letters Patent is:

l. In a pneumatic tool comprising a cylinder, and a piston in saidcylinder, a valve unit including two stationary members spaced one fromthe other, having opposed annular channels and having openingscommunicating respectively with the opposite ends of said cylinder, anannular wall extending about the space between said stationary memberson the outer side of said channels and having substantially radial portsleading to the space between said stationary members and communicatingwith said. channels, means for connecting said ports with a source ofsupply of air under pressure, and a disk valve member mounted betweenthe inner portions of said stationary members for movement into and outof engagement with said stationary members alternately to interrupt thecommunication between the channel and the opening V,in the member withwhich it is in engagement and to establish communication between thechannel and the opening in the other member.

2. In a pneumatic tool comprising a cylinder and a piston in saidcylinder, a valve unit including two stationary members spaced one fromthe other, having opposed annular channels and having openingscommunicating respectively with the opposite ends of said cylinder, anannular wall extending about the space between said stationary memberson the outer side of said channels and having substantially radial portsleading to the space between said stationary members, means forconnecting said ports with a source of supply of air under pressure, adisklike valve member arranged betweenA said stationary members toseparate the openings there.- in, extending into the space between theopposed channels and having peripheral grooves in line wtih the ports insaid annular wall and communicating with said annual channels, saidvalve member being movable into engagement with said stationary membersalternately to interrupt communication between the channel and theopening of that member with which it is in engagement and to establishcommunication between the channel and the opening in the other member.

3. In a pneumatic tool comprising a cylinder and a piston in saidcylinder, a valve unit including two stationary members spaced one fromthe other, having opposed annular channels and having openingscommunicating respectively with the opposite ends of said cylinder, anannular wall extending about the space between said stationary memberswith its inner edge adjacent the outer side of said channel, a disk-likevalve member slidably mounted within said annular wall and arrangedbetween said stationary members to separate the openings therein, theadjacent edges of said annular Wall and said valve member having opposedperipheral grooves, and said annular wall having substantially radialports leading to the groove therein and also having peripheral notchesto connect said groove with said channels, and means for connecting theouter ends of said ports with a source of supply of air under pressure,said valve member being movable by the action of the air into engagementwith said stationary members' alternately to interrupt communicationbetween the channel and the opening in that member with which it is inengagement and to establish communication between the channel and theopening in the other member.

4. In a pneumatic tool comprising a cylinder and a piston in saidcylinder, and having a `cavity at the rear end of said cylinder, a valveunit mounted in said cavity and spaced from the Wall thereof to providea circumferential passageway, means for connecting said passageway witha source of supply of air under pressure, said valve unit including afront member having an opening communicating with the rear end of saidcylinder and having a rearwardly facing channel surrounding saidopening, a rear member having an opening communicating with the frontend of said cylinder and having a forwardly facing annular channelsurrounding the opening therein and arranged in opposed relation to thechannel in said front member, an annular wall extending about the spacebetween said front and rear members at the outer side of said channelsand having ports connecting said circumferential passageway With saidannular channels, and a movable valve member arranged within saidannular wall to separate the openings in said front and rear members onefrom the other and slidably mounted for fore and aft movement withrelation to the front and rear members to alternately establish andinterrupt communication between the channels and openings of said frontand rear members respectively, said valve member having peripheralgrooves arranged in line with the ports in said annular wall, and saidannular wall having notches to connect said grooves and said ports withsaid annular channels.

WILLIAM A. SMITH, JR.

